Biological Nutrient Removal: Where We Have Been, Where We Are Going?
The paper covers the early research that led to the development of the biological nutrient removal (BNR) technology that is widely practiced today then looks at the present and future of BNR. Presently only suspended and attached growth biological processes or a combination of the two are used to reduce nitrogen concentration to around 3 mg/L. New technologies such as the SHARON® and ANAMMOX® processes are being developed to utilize autotrophic
denitrification when treating high strength ammonia streams, reducing or eliminating the need for carbon addition. The concentration of recalcitrant dissolved organic nitrogen (rDON) which cannot be removed by biological processes will determine the limits to which nitrogen can be reduced. Phosphorus can be removed effectively to very low levels by using chemicals; however, biological treatment can remove phosphorus to between 0.1 and 0.15 mg/L, reducing
the amount of chemical required for removal to very low levels.